1. Field of the Invention
The present invention relates to an electrode assembly, and more particularly, to an electrode assembly having a stepped portion formed by at least two electrode units having different sizes.
In addition, the present invention relates to a battery cell, a battery pack, as well as a device including the electrode assembly, and a method of manufacturing a battery including the electrode assembly.
2. Description of the Related Art
Demand for secondary batteries has markedly increased with the development and increasing usage of mobile devices, and particularly, lithium secondary batteries are widely used as power sources of various electronic products such as mobile devices owing to the high energy density, high operating voltage, easy-to-store characteristics, and long lifespan thereof.
Generally, lithium secondary batteries are formed by disposing an electrode assembly and an electrolyte in a battery case and sealing the battery case. Lithium second batteries may be classified into cylinder, prism, and pouch types according to the shapes thereof, and lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries according to the types of electrolytes.
Demand for thin prism or pouch type batteries increases as the size of mobile devices decreases, and particularly, pouch type batteries are noteworthy because pouch type batteries are light.
Electrode assemblies used in battery cases may be classified as jelly-roll (winding), stacked, and stacked and folded (combination) types according to the structures thereof.
A jelly-roll type electrode assembly may be formed by coating metal foil used as a current collector with electrode active materials, pressing the metal foil, cutting the metal foil into bands having a predetermined width and length, dividing the bands into positive and negative electrodes using a separator film, and spirally winding the separating film. A stacked type electrode assembly may be formed by vertically stacking a negative electrode, a separator, and a positive electrode. A combination type electrode assembly may formed by arranging a plurality of unit cells each including a stack of negative electrode/separator/positive electrode on a sheet of separating film and stacking the unit cells by folding the separating film.
Since electrode assemblies of the related art are generally manufactured by stacking unit cells or electrodes having the same size, it may be difficult to manufacture batteries having various designs using such electrode assemblies. Furthermore, if the designs of batteries are changed, processes such as electrode manufacturing processes, electrode stacking processes, or electric connection processes may become complicated or difficult to perform.
Since recent mobile devices have various shapes, it is necessary to manufacture batteries having various shapes for such mobile devices. Therefore, electrode assemblies having structures suitable for manufacturing batteries having various shapes or easily changing the shapes of batteries are necessary to follow or satisfy design requirements on recent (mobile) devices.
An aspect of the present invention provides an electrode assembly suitable for providing various battery designs.
An aspect of the present invention also provides an electrode assembly having a thin shape and satisfactory electric capacity characteristics.
Aspects of the present invention also provide a battery cell, a battery pack, and a device including the electrode assembly.